Robots again

From: Doug Yowza <yowza_at_yowza.com>
Date: Tue Mar 17 22:13:21 1998

On Tue, 17 Mar 1998, Bill Yakowenko wrote:

> Doug Yowza <yowza_at_yowza.com> wrote:
> ] To be fair, analog computers can do things digital computers can't. For
> ] example, a digital computer can only approximate 1.0/3.0 whereas an
> ] analog box has no trouble with this. Certain ops would also be much
>
> Actually, you've got that backwards. Contained in your message above
> is a totally accurate digital representation of 1/3. Oh, there it is
> again, at the end of that sentence. It is an analog measure of this
> that would lack precision.

Argh, semantics. OK, how about "a binary representation of the *result*
of the expression 1.0/3.0 will always be an approximation." And "an
analog representation of the *result* of the expression 1.0/3.0 *can* be
exact." For example, I could build an analog (i.e, continuous valued)
machine whose ALU performed division by pouring water from one glass into
another (in a loss-free vacuum chamber if you'd like). The glass/water
accululator would be exactly 1/3 full after the above calculation.

Makes you thirsty just thinking about it, doesn't it? :-)

> OBCC: Is there any such thing as a stored-program analog computer?
> I guess Babbage's analytic engine would fit that category, but all
> of the other analog "computers" that I've heard of (not many) just
> performed some fixed calculation. In my book, a stored program with
> sequence-control makes the difference between a computer and a
> calculator, manufacturer's labelling notwithstanding.

Wasn't Babbage's engine mechanical? Mechanical computers are still
"digital" in the sense that they compute using discrete values/states.
Here is an example which proves that analog machines can execute stored
programs: "go to the store." If you remembered that and went to the
store, then you just answered your own question. (If you didn't go to the
store, you have a bug. :-)

-- Doug
Received on Tue Mar 17 1998 - 22:13:21 GMT